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PubMed2006

The effects of lumbar massage on muscle fatigue, muscle oxygenation, low back discomfort, and driver performance during prolonged driving.

An increasing dependence of society on automobiles for both work and leisure and the corresponding increase in time spent seated in the car has been correlated with a greater risk of low back pain and absence from work (Porter and Gyi 2002). This study examined the effects of three types of lumbar massage units on seating comfort, muscle fatigue, muscle oxygenation, muscle blood flow and driving performance during a 1 h simulated driving task. Electromyographic (EMG) signals were recorded from the right and left thoracic and lumbar erector spinae musculature. Average EMG (AEMG), mean power frequency (MPF), gaps and amplitude probability distribution function (APDF) parameters were analysed from the three massage seats and compared to a control seat. Near infrared spectroscopy (NIRS) and skin temperature from the right thoracic and lumbar erector spinae were used as an indication of muscle oxygenation and blood flow throughout the driving task. Ratings of perceived discomfort were used to assess driver discomfort, and driving performance was assessed by calculating mean lap times for the duration of each driving trial. The results showed statistically significant increases in skin temperature compared with the control seat after 60 min of driving. The NIRS results reflected these trends although the results were not statistically significant. AEMG and MPF measures showed no significant differences between the seats. MPF measures were found to increase over time, effects attributed to increases in muscle temperature. Gaps and APDF analyses revealed greater rest times and lower activation levels, respectively, with the control seat, which could result in increased loading of passive structures. This study demonstrated the beneficial effects of lumbar massage systems in increasing muscle blood flow and oxygenation. Although EMG parameters were not significantly different, the trends support the significant blood flow results. Future research should include longer driving times and adjustments in EMG measures to account for the effects of increasing muscle temperature on AEMG and MPF measures.

Adult↗
PubMed1989

Lumbar muscle fatigue and chronic lower back pain.

There currently is a clinical need for an objective technique to assess muscle dysfunction associated with chronic lower back pain. A Back Analysis System for objectively measuring local fatigue in the back extensor muscles is presented. The reliability and validity of this technique was evaluated by testing chronic low-back pain patients and control subjects without back pain. Concurrent surface electromyograms (EMG) were detected from multiple back muscles during sustained isometric contractions at different force levels of trunk extension. Median frequency parameters of the EMG power density spectrum were monitored to quantify localized muscle fatigue. Results indicated: 1) high reliability estimates for repeated trials; 2) significant differences (P less than 0.05) in median frequency parameters between lower back pain patients and control subjects for specific combinations of contractile force level and muscle site tested; 3) Median Frequency parameters correctly classified lower back pain and control subjects using a two-group discriminant analysis procedure. The applicability of this technique as a treatment outcome measure and diagnostic screening method for lower back pain patients is discussed.

Adult↗
PubMed2006

Spinal range of motion, muscle endurance, and back pain and function at least 20 years after fusion or brace treatment for adolescent idiopathic scoliosis: a case-control study.

STUDY DESIGN: A consecutive series of patients with adolescent idiopathic scoliosis (AIS), treated between 1968 and 1977 before 21 years of age with either distraction and fusion using Harrington rods (ST, n = 156; 145 females and 11 males) or with brace (BT, n = 127; 122 females and 5 males), were followed at least 20 years after completion of the treatment. OBJECTIVES: To determine the long-term outcome in terms of spinal mobility and muscle strength and its possible correlations to present back pain and function in patients surgically or brace treated for AIS. SUMMARY OF BACKGROUND DATA: Few reports on long-term outcome on these variables have previously been presented for this group of patients. METHODS: A total of 135 (87%) of ST and 102 (80%) of BT patients underwent a complete examination by two unbiased observers incl. evaluation of lumbar muscle endurance and spinal mobility, curve size (Cobb method), validated questionnaires in terms of general and disease-specific quality of life aspects, as well as present back function and pain. An age- and sex-matched control group of 100 persons was randomly selected and subjected to the same examinations. RESULTS: For both ST and BT groups, lumbar spinal motion as well as muscle endurance were significantly decreased compared with controls. For ST patients, better lumbar extensor and flexor muscle endurance or lumbar spinal mobility correlated with a better physical function. The length of fusion into the lumbar spine correlated inversely with lumbar range of motion, but the finger-floor distance was not affected. BT patients with reduced lumbar spinal mobility experienced lumbar back pain more often than controls. CONCLUSIONS: For both brace treated and surgically treated AIS patients, spinal mobility and muscle endurance were reduced more than 20 years after completed treatment. The physical function was not severely restricted.

Adolescent↗
PubMed2001

Do oarsmen have asymmetries in the strength of their back and leg muscles?

The aim of this study was to establish whether asymmetry of the strength of the leg and trunk musculature is more prominent in rowers than in controls. Nineteen oarsmen and 20 male controls matched for age, height and body mass performed a series of isokinetic and isometric strength tests on an isokinetic dynamometer. These strength tests focused on the trunk and leg muscles. Comparisons of strength were made between and within groups for right and left symmetry patterns, hamstring: quadriceps ratios, and trunk flexor and extensor ratios. The results revealed no left and right asymmetries in either the knee extensor or flexor strength parameters (including both isometric and isokinetic measures). Knee extensor strength was significantly greater in the rowing population, but knee flexor strength was similar between the two groups. No difference was seen between the groups for the hamstring: quadriceps strength ratio. In the rowing population, stroke side had no influence on leg strength. No differences were observed in the isometric strength of the trunk flexors and extensors between groups, although EMG activity was significantly higher in the rowing population. Patterns of asymmetry of muscle activity were observed between the left and right erector spinae muscles during extension, which was significantly related to rowing side (P < 0.01). These observations could be related to the high incidence of low back pain in oarsmen.

Adult↗
PubMed1995

Regional muscle loss after short duration spaceflight.

BACKGROUND: Muscle strength and limb girth measurements during Skylab and Apollo missions suggested that loss of muscle mass may occur as a result of spaceflight. Extended duration spaceflight is important for the economical and practical use of space. The loss of muscle mass during spaceflight is a medical concern for long duration flights to the planets or extended stays aboard space stations. Understanding the extent and temporal relationships of muscle loss is important for the development of effective spaceflight countermeasures. HYPOTHESIS: We hypothesized that significant and measurable changes in muscle volume would occur in Shuttle crewmembers following 8 d of weightlessness. METHODS: MRI was used to obtain the muscle volumes of the calf, thigh and lower back before and after the STS-47 Shuttle mission. RESULTS: Statistical analyses demonstrated that the soleus-gastrocnemius (-6.3%), anterior calf (-3.9%), hamstrings (-8.3%), quadriceps (-6.0%) and intrinsic back (-10.3%) muscles were decreased, p < 0.05, compared to baseline, 24 h after landing. At 2 weeks post recovery, the hamstrings and intrinsic lower back muscles were still below baseline, p < 0.05. CONCLUSIONS: These results demonstrate that even short duration spaceflight can result in significant muscle atrophy.

Adult↗
PubMed2001

Back and abdominal muscle function during stabilization exercises.

OBJECTIVES: To assess the paraspinal and abdominal muscle activities during different therapeutic exercises and to study how load increment produced by varying limb movements and trunk positions could affect these muscle activities. DESIGN: A cross-sectional study comparing muscle activities between men and women. SETTING: Rehabilitation clinic in university hospital. PARTICIPANTS: Twenty-four healthy volunteers (14 women, 10 men) aged 21 to 39 years. INTERVENTIONS: Subjects performed 16 different therapeutic exercises commonly used to treat low back pain. MAIN OUTCOME MEASURES: Surface electromyography was recorded from the paraspinal (T9, L5) and abdominal (rectus abdominis, obliquus externus) muscles during these exercises. Average electromyographic amplitudes obtained during the exercises were normalized to the amplitude in maximal voluntary contraction (% MVC) to produce interindividually comparable muscle activity assessments. RESULTS: Mean average normalized electromyographic amplitudes (% MVC) of the exercises were below 50% MVC. At L5 level, the multifidus muscle activities were significantly higher (p <.05) in women than in men, whereas no significant difference was found at T9 level. Similarly, rectus abdominis and obliquus externus activities were significantly higher (p <.001, p <.05) in women than in men. Load increment in hands or unbalanced trunk and limb movements produced higher paraspinal and abdominal muscle activities (p <.05). CONCLUSIONS: Simple therapeutic exercises are effective in activating both abdominal and paraspinal muscles. By changing limb and trunk positions or unbalancing trunk movements, it is possible to increase trunk muscle activities. Women were better able to activate their stabilizing trunk muscles than men; but it is also possible that men, having a much higher degree of strength on maximal contraction, only need to activate a smaller amount of that maximum to perform a similar activity.

Abdominal Muscles↗
PubMed1999

Electromyographic responses of back and limb muscles associated with spinal manipulative therapy.

STUDY DESIGN: Ten young, asymptomatic male subjects underwent 11 clinically relevant spinal manipulative treatments along the length of the spine to test the magnitude and extent of reflex responses associated with the treatments. OBJECTIVES: To determine the magnitude and extent of reflex responses elicited by spinal manipulative treatments. SUMMARY OF BACKGROUND DATA: Spinal manipulative treatments have been associated with a reflexogenic relief of pain and a loss of hypertonicity in muscles within the treatment area. However, there is no study in which results show the probability of occurrence or the extent of reflex responses during spinal manipulative treatments. METHODS: Asymptomatic subjects received spinal manipulative treatments on the cervical, thoracic, and lumbar levels and on the sacroiliac joint. Reflex activities were measured using 16 pairs of bipolar surface electrodes placed on the back and proximal limb musculature. The percentage of occurrence and the extent of reflex responses in the back and proximal limb musculature were determined. RESULTS: Each treatment produced consistent reflex responses in a target-specific area. The reflex responses occurred within 50-200 msec after the onset of the treatment thrust and lasted for approximately 100-400 msec. The responses were probably of multireceptor origin and were elicited asynchronously. CONCLUSIONS: This is the first study in which results show a consistent reflex response associated with spinal manipulative treatments. Because reflex pathways are evoked systematically during spinal manipulative treatment, there is a distinct possibility that these responses may cause some of the clinically observed beneficial effects, such as a reduction in pain and a decrease in hypertonicity of muscles.

Adult↗
PubMed2001

Active therapy for chronic low back pain: part 2. Effects on paraspinal muscle cross-sectional area, fiber type size, and distribution.

DESIGN: Randomized prospective study to compare the effects of three types of active therapy on the back muscle structure of chronic low back pain patients. OBJECTIVES: To analyze the effects of 3 months active therapy on gross back muscle size and muscle fiber type characteristics and their relationship to changes in muscle function. SUMMARY OF BACKGROUND DATA: Many studies have documented a diminished muscular performance capacity in cLBP patients, but few have supported this with evidence of alterations in either the macro- or microscopic structure of the paraspinal muscles. Investigations of the changes in muscle structure following active rehabilitation are even rarer. METHODS: Assessments of trunk muscle cross-sectional area (using MRI), erector spinae fiber size/type distribution and pathology (percutaneous biopsy), and muscle function (see Part 1) were made in a group of 59 individuals with cLBP, who were participating in a randomized trial of active therapies for cLBP (physiotherapy, muscle training on devices, aerobics). RESULTS: Fifty-three out of 59 patients (90%) completed the therapy. At baseline, significant correlations were observed between the size of the paraspinal muscles and isometric back extension strength (P=0.0001), and between the proportional area of the muscle occupied by each fiber type and the fatigability of the muscle (P=0.012). Following therapy, there were small (few percent) increases in trunk muscle size in the aerobics and physiotherapy groups and a similarly slight decrease in the devices group. Changes in erector spine size correlated only weakly and nonsignificantly with changes in back extension strength. There were no major changes in fiber type proportion or fiber size in any group following therapy. CONCLUSION: Three months active therapy is not sufficient to reverse the typical "glycolytic" profile of the muscles of cLBP patients or to effect major changes in backmuscle size. The alterations in muscle performance observed (increased strength and endurance; Part 1) werenot explainable on the basis of structural changes within the muscle.

Adult↗